diff --git a/include/camera/camera2/ICameraDeviceUser.h b/include/camera/camera2/ICameraDeviceUser.h
index a7bf8ab..4d8eb53 100644
--- a/include/camera/camera2/ICameraDeviceUser.h
+++ b/include/camera/camera2/ICameraDeviceUser.h
@@ -140,6 +140,11 @@
     virtual status_t        prepare(int streamId) = 0;
 
     /**
+     * Preallocate up to maxCount buffers for a given output stream asynchronously.
+     */
+    virtual status_t        prepare2(int maxCount, int streamId) = 0;
+
+    /**
      * Free all unused buffers for a given output stream.
      */
     virtual status_t        tearDown(int streamId) = 0;